#define _CRT_SECURE_NO_WARNINGS 1

#include <stdio.h>
#define OFFSETOF(str, part) ((char*)(&str.part) - (char*)(&str)) 

struct stu
{
	char name[20];
	int year;
	char a;
	int b;
};
int main()
{
	struct stu boy = { 0 };
	int off_set_of = OFFSETOF(boy, a);
	printf("%d\n", off_set_of);
	return 0;
}